Method and apparatus for reclaiming lubricating oil



June 24, 1930. c. D. MILLER aktozmuj C., D. MILLER June 24, 1930.

METHOD AND APPARATUS FOR RECLAIMING LUBRICATING OIL Filed Dec. '17. 19274 Sheets-Sheet 3 Alli Siler/ami June 24, 1930. v C. D. MILLER 1,768,209

METHOD AND APPAR'ATUS FOR RECLAIMING LUBRICATING OIL Filed Dec. 17,192'? 4 Sheets-Sheet 4 C//ZL 0. MILLE/3,

attozumj Patented .lune 24, 1930 UNITED STATES CARL D. MILLER, F MILLIS,MASSACHUSETTS METHOD AND APPARATUS FOR RECLAIMING LBVRICATING OILApplication filed December 17, 1927. Serial No. 240,842.

The present invention relates to the reclaiming of used lubricating oildrained from automobile crankcases and similar engines, and aims toprovide an improved method and apparatus whereby such oil may be put incondition for further use.

It is now fairly well established that such oil is largely lubricatingoil of unimpaired quality. Such chemical breakdown of the oil as occursin service is a breakdown of the weaker constituents, rather thanof thestronger,and is so complete that the resulting products are not oil atall, and can be separated from the remaining oil alon with other foreignmatter, solid and liqui that is taken up .by the oil during service. Theproblem of reclaiming this oil is therefore simply one of effecting aphysical separation of the foreign matter from the oil.

Various methods have been proposed for effecting this separation, suchmethods generally comprising a step wherein the solid matter is removedfrom the oil by washing, and a second step wherein liquid impurities 25are removed by distillation.

This general procedure is followed in the present invention, but certaindifferences occur in the manner of executing the steps thereof. In thewashing ste/Ip, it has been 3o customary to mix a solution o soap orwashing powder with the oil to be cleaned, agitating the mixture inorder-to expose all of the oil to the action of the washing solution.When this is done, however, the difiiculty occurs that the oil and washvwater form an emulsion which is practically impossible to break down,so that the oil itself is largely lost in the emulsion. In the presentinvention, the oil and washing solution are brought into thoroughcontact with each other without, however, .forming an emulsion, with theresult that all the solid matter can be separated from the oil in anopen tank without difficulty, the method being effective to remove allthe solid matter, from the nest carbon or metal particles to nails,bolts and pieces of cloth and waste.

As to the theory of the washing process, the following may be said: Thesolid par- 60 ticles, such as carbon particles, apparently adsorb theoil and are thereby held to an extent in suspension, so that allowing-the oil to stand will not result in settling out these particlesvsatisfactorily. The film of adsorbed oil may, however, be replaced bythe washing solution, even though these liquids themselves do not mix.That. is, the washin solution will, under suitable conditions, orce itsway tothe surface of the solid particle and displace the film of oiladhering thereto, the carbon particle being thereby loaded down by acoating of washing solution and caused to sink faster than it would byits own weight alone. Most important, however, the carbon particles whenimpregnated with the washing solution will stick together when they comein contact, forming comparatively large agglomerations that sink muchmore rapidly than the particles will sink separately. Theseagglomerations settle Ithrough the oil, forming a layer of black sludgeat the bottom thereof, the oil above this layer being thereby entirelyfreed of solid matter. Below this layer of sludge iswnormally a layer ofwashing solution, since the particles in the sludge mostly do not sinkthrough the wash water, apparently because a suiiicient amount of oil isentangled with the`particles to make the slud e lighter than the washingsolution itsel.

In order to enable the washing solution to reach all of the suspendedparticles, it is necessary that the two liquids be brought into intimatecontact with each other. As above explained, previous methods foreffecting such contact have frequently resulted in the formation of anemulsion which was virtually impossible to break down. The presentmethod avoids this difiiculty in that the mechanical action between thewash water and the oil takes place without substantial violence, suchviolence being altogether unnecessary in accomplishing the theoreticaleffect above discussed. For the action on the particles, contact is allthat is needed, a fact which can be appreciated by considering theenormous molecular forces exerted between the surface of the solidparticle and the adsorbed lm of liquid, in comparison to which anyoutside force is entirely unappreciable.

A practical embodiment of an apparatus for carrying out the process ofthe present invention is illustrated in the accompanying drawings, inwhich:

Fig. 1 is a diagrammatic layout of the apparatus; Y

Fig. 2 is a plan view of the still with the cover removed;

Fig. 3 is a vertical section of the still;

Fig. 4 is a section taken on line 4-4 of Fig. 3;

Fig. 5 is an enlarged detail of the vapor outlet of the still;

Fig. 6 is an elevation of the distillate cooler;

Fig. 7 is a sectional view of the same taken on the line 7--7 of Fig. 6;

Fig. 8 is an enlarged sectional view taken on the line 8-8 of Fig. 1;

gig. 9 is an elevation of the washing tank; an

Fig. 10 is a sectional view taken on the line 10-10 of Fig. 9.

Referring more particularly to the drawings, 15 represents the washingtank which is surrounded by a jacket 16 whereby the contents of the tankmay be heated, the jacket being further surrounded by heat insulatingmaterial 14, as shown in Figs. 9-

and 10. At the bottom of tank 15 is provided an inlet and outlet pipe17, and a baiiie. 18 is positioned over the mouth of the pipe so thatwhen liquid enters through pipe 17 it will be deflected outwardly ratherthan passing directly upward. At the top of tank 15 is formed a trough20 which is fed by a wash water conduit 2l and has an overflow pipe 33leading therefrom, said pipe being normally closed by a cap 34. Theinner edge 22 of trough 2O is at a lower level than the outer edge, withthe result that the wash water leaving pipe 21 will fill trough 20 andthen overflow into the tank '15. During the washing operation, the tankwill normally contain a layer 23 of the oil being cleaned, a layer 24 ofsludge which has been'removed from the oil, and a layer 25 of wash waterbeneath the sludge. The wash water overflowing from trough 20 will tendto cling to the inner wall 26 of the tank, and will flow downwardlythereover for some distance in a substantially unbroken sheet, impartinga minimum of agitation to the oil 23. The passage of this sheet of washwater, however, tends to set up a circulation within the oil layer, withthe result that the oil is sufliciently stirred to eventually bring it-all into contact with the descending sheet of wash water. An electricheater 60 of any usual design is connected to jacket 16 in the usualmanner to provide for heating the heating medium, preferably water, usedtherein. While the washing operation is going on the tank and itscontents are heated by means of the jacket 16. Heating tends to set up acirculation in the oil, and this tendency is partly counterbalanced by,or partly counterbalances, the circulating tendency of the descendingwash water.

The water which is to be used for washing is introduced through an inletpipe 27 discharging into a standpipe 28 which is provided with a balile30 which is provided to facilitate the escape of air or other gasescontained in the water as it comes from the mains. The standpipeconnects with pipe 17, which is in turn connected to the interior ofthewashing tank and with wash water conduit 21. A pump 32 is positioned inconduit 21 to provide circulation of the wash water by withdrawing itfrom the bottom of tank 15 and discharging it into the trough 20.

As seen in Figs. 2, 3, 4 and', still 35 is provided with an insulatinglayer 29, and has an inlet opening adjacent its top which is normallyclosed by a plug 31. A steam pipe 36 leads from a steam boiler 37 andconnects, through a trap 38, with a pipe-39 which has a horizontal arm40 provided with a series of apertures 41 for admitting steam into thebottom of the still. The steam enters through pipe 36, any watercontained therein being caught in trap 38, Where the high temperature ofthe oil converts it into steam. Pipe 39 'is bent into a goose neck asshown, and the effect of the hot oil is to superheat the steam passingthrough the pipe, with the result that when the steam emerges from theopenings 41 and comes into direct contact with the oil, it issuperheated. No water is allowed to come into direct contact with theoil, as this is 'objectionable in the explosive suddenness with whichwater is converted into steam in the case of such contact when the oilis hot. The goose neck is provided to prevent the oil from running intothe water trap 38 before the steam is turned on. A further precaution isto avoid the formation of a vacuum in boiler 37 when it is turned off,as this will draw the oil out into the trap 38 and into the boiler. Thisis prevented by providing a cock 101 in pipe 36, which cock is alwayskept slightly open.

The steam issuing from apertures 41 passes outwardly through the hot oiland greatly facilitates the evolution of its more volatile constituents.These more volatile constituents pass upwardly around a splash plate 42into a dome 43 which, unlike the body of the still, is not insulated. Atrough 45 is provided to catch the condensate of such vapors as arecondensed in the dome, such condensate passing out through an outletpipe 44. Pipe 44 connects with a condenser 46 which may be simply in theform of an inclined pipe surrounded by a cooling water jacket.

The still 35 is heated by any suitable means, preferably the electricheating ele ments 92 shown in Fig 3, which project upwardly from thebottom of the still. Boiler 37 is also preferably heated by means of anelectric heating element 93, a steady, constant supply of steam beingrequired which is best furnished by electric heat.

As a guide to the stage to which the distillation has progressed, a cock94 is provided in the still, whereby test samples of the oil may bewithdrawn from time to time. A sheath 95 also projects inwardly from thewall of the still, and is adapted to receive a chemical thermometer 96.

The vapors and condensate issuing from condenser 46 pass into a cooler48 which comprises a receiving chamber 50 having a cover 51 looselymounted thereon so as to be raised if the pressure in chamber 50 eX-ceeds a certain limit. A partition 52 forms the bottom of chamber 50,and a worm 53 has one of its ends extending through the partition tocommunicate with chamber 50, and its other end 54 extending through thebase of the cooler into a distillate tank 55. A pipe 56 is connected atthe bottom of the tank 55, and connects with an inlet pipe 57 and anoutlet pipe 58, and an overflow 59 is provided adjacent the top of thetank. The mixed hydrocarbons and water coming from cooler 48 separate bygravity in tank 55, and the hydrocarbons may then be removed byadmitting water from the mains through inlet pipe 57 until thehydrocarbons have flowed out through overflow 59, Valve 97 is thenclosed and valve 98 opened, allowing the residue, consisting chiefly ofwater, to flow out of the tank.

The means for cooling the residue from still 35 lis as follows. A pipe61, having a' valve 67, leads from the bottom of the still t0 a cooler62 which is preferably vertically disposed adjacent the still. The oilpipe 64 within the cooler is preferably pinched or deformed as shown, sothat the oil does not flow therethrough in a smooth stream, but isbroken up by the deformations of the pipe. Pipe 64 terminates in anoutlet pipe 65 which is shaped to deliver the cooled oil to a suitablecontainer. A pump 63 is provided in pipe 65 to draw the oil from thestill through the cooler 62. The water piping of the system is soarranged that heat yielded either by the cooling of oil in cooler 62 orby the condensin of vapors in condenser 46 can be utilize lin heatingthe contents of the washing tank 15. The cooling water from the mainsenters at 70, passes through cooler 48 and pipe 71 until the system isfilled with water. Thereupon, valve 82 is closed and valve 81 opened, sothat the water flowing from cooler 48 is dis charged, while the water inthe rest of the -system circulates without any addition to orsubtraction from its volume. The water jacket of condenser 46 isconnected, by pipes 72 and 73, to the oil cooler 62 and to an expansiontank 74, having an overflow pipe 100. A return pipe 75 leads from tank74 to jacket 16. A pipe 77 connects the lower portion of jacket 16 tothe lower portion ot cooler 62, and a pipe 78 connects pipe 77 with thewater jacket of condenser 46. Valves 80, 81, 82, 85, 86, 87 and 88 arepro vided in the cooling system as shown in Fig. 1, and permit severalalternative arrangements as to cooling.

Assuming that a batch of oil is being cooled in cooler 62, and that acold batch of oil has been placed in tank 15, valve 82 will be closed,the remainder of the valves being open. The heated water will then passupwardly out of cooler 62, through pipe 73, tank 74 and pipe 75 tojacket 16, where it gives up its heat to the cold oil. turns throughpipe 77 to the cooler 62. The

.Water from cooler 62 may also pass through 7 pipe 72, condenser 46,pipe 78 and pipe to the bottom of the cooler without passing throughjacket 16, but this is ordinarily not objectionable because more thanenough heat is generated by cooler 62 to bring the oil in tank 15 up tothe desired washing temperature, the heater 60 being necessary only whenthere is no hot oil to be cooled in cooler 62. Valve 85 is provided,however, so that condenser 46 may be cut out of the system if desired.It will be readily understood that the heat generated 'in condenser 46may be used instead of that from cooler 62 to heat the water if desired.Valve 87 may be closed, to prevent further heating of the washing tankby waste heat from the still, and if desired valve 82 may be opened andvalve 81 closed, so that cold water entering by pipe passes through thesystem and out from the tank 74 through `pipe 100.

The operation is as follows. A batch of oil to be cleaned is poured intotank 15, filling it to within 10 or 12 inches of the top. Valves 83 and84 are kept closed while the oil is being poured in. Valve 84 is thenopened, allowing water to run into the bottom of tank 15, the incomingwater being deflected horizontally by the baiile 18 so that it does notunduly disturb the body of oil above it. The admission of water iscontinued until the oil above it is within about 2 inches of the top ofthe tank. The oil is then heated by means of the water entering throughpipe 75, as above described, or by means of heater 60 if necessary,until the oil is raised to a temperature of 180 to 200o F., at whichtemperature the oil boils slightly. As soon as the oil has becomenoticeably hot, the pump 32 is started, taking the wash water from thebottom of It then re! them apparently clear.

the tank to the trough 20, filling the trough and causing the water tofiow over the rim 22 and down the inner surface of the tank. The tank iscarefully leveled, so that the water passes over in a thin uniform sheetall around. The descending sheet of wash water acquires only a very lowvelocity, so that it passes through thel oil gently, continuing in largemeasure on down the tank still as a continuous sheet between the walland the oil. After the pump has been started, about 5 pounds of washingpowder of any of the usual brands is put into the tank and stirred down.This is dissolved by the water, which is continued in circulation forthree or four hours. The washing powder has an immediately noticeableeffect on the Water as it runs down the exposed surface between the oiland the rim 22, in causing the water to adhere to the metal in asubstantially uniform sheet, whereas the pure water fiows over thissurface in irregular rivulets.

The effect of the washing on the carbon particles in the oil soonbecomes apparent.,

Before the washing has begun, the carbon will be diffused ratheruniformly through the oil in very fine particles, giving the oil an inkyappearance. When the oil is heated, the particles acquire a noticeabletendency to gather together in roups, and after the washing has been uner way for a time, they will be seen to have gathered 1n masses whichappear as black specks of considerable size, leaving the oil betweenThis agglomeration or coagulation naturally increases enormously thespeed with which the carbon will settle when the oil is left at rest,and the weight of the wash water adsorbed by the carbon accentuates thistendency. After three or four hours of this Washing, all of the carbonthroughout the oil is acted on by the wash water and coagu'lated. Themechanical effect of the downward stream of wash water and of the heatapplied to the tank is to set up convection currents, producing variouseddying and swirling motions, not of a violent nature, but serving tobring the oil and carbon particles into contact with the wash water andto bring the carbon particles into contact with each other to form thelarger agglomerations. The effect of heating is to increase the fluidityof the oil thereby increasing the eddying and swirling motions whichbring the water and carbon particles into contact. Heat also hastens theaction of the wash water on a particle when the contact is made. Also,by decreasing the surface tension, it decreases the tendency of the oiland the wash water to emulsify.

When the washing operation is complete, the tank is covered t0 keep theoil from cooling at the top and producing convection currents. Cap 34 isremoved and trough 20 emptied of Wash water and cleaned. The 'Oil isallowed to settle overnight or longer if convenient, the insulation 14serving to prevent loss of heat, so that the fluidity of the oil ismaintained during the settling.

When settling is complete, the clean oil is forced out of the tank byrunning water in through pipe 17 from standpipe 28. The admission ofwater is regulated by valve 84, the oil being slowly pushed up frombelow by the Water so as to cause it to flow over the rim 22 into thetrough 20, out the spout 33 and into the receiving vessel. en the layerof sludge approaches the top of the tank, the stream of oil is divertedto another container, so that no sludge gets into the clean oilpreviously run off. The sludge forms a sharply defined layer below the011, and the oil immediately above the sludge is entirely clean if thesludge has not been disturbed during the operation. The final layer ofoil is run off until only a very thin layer remains above the sludge,after which any oil remaining in the trough is pushed out by means of apaint brush. In some cases, under the best conditions, the oil willdrain completely from the sludge, as from a solid surface, withoutbringing any sludge over into the trough. The sludge may then be dippedout and the water run out by opening the drain valve 83. If any sludgeis found adhering to the sides of the tank, it can be washed or brusheddown, leaving the tank ready for another batch of o il. Metallicimpurities such as filings or nails will be found at the bottom of thetank.

The distillation is next performed, the clean oil being transferred tothe st1ll 35, where it is heated electrically to a temperature rangingfrom 400 to 600 F. depending upon the nature of the dlluents and thedesired viscosity of the residue.

In distilling, the steam should not be started through the oil until theoil has reached a temperature Well above the boiling point of water, andyet sufficiently low that the vapors will not be evolved too rap1d1ly orviolently, which would cause o1l to be carried along with r4the vapors.Usually, the steam is admitted when the oil reaches a temperature ofabout 300 F. keeping all the heaters on in the oil until the temperaturereaches 600, and then turning ofI1 .all except one of the heaters, whichmaintains the temperature at approximately 600,- at

which temperature the distillation is con` tinued for some time.

When steam is introduced into the still through the pipe 40, it passesup through the oil in the still from the bottom. This greatlyfacilitates the distillation, as is well known. The evolved vapors,consisting of substances resembling kerosene mixed with steam, pass intothe dome 43 and out the outlet 44 into the condenser 46. If thetemperature of the still is kept constant, the volume of hydrocarbonsevolved will naturally decrease as distillation progresses, and whenthis Ivolume has become equal to the volume of the water condensed fromthe steam, it will generally be found that distillation cannot beprofitably prolonged. Where a temperature of 600 F. is used, the lastrun will be a light lubricant.

The vapors evolved in still 35 are chiefly condensed in condenser 46,but any remaining vapors are passed, along with the condensate, throughcooler 48, where they meet the cold incoming water from the mains, whichcompletes the condensation. The distillate then passes into container55, where the water and hydrocarbons separate by gravity and the latterare removed as described above.

Various changes may be made in the specific embodiment above described.Thus, While only one washing tank is shown in the drawings, a pluralityof such tanks may be used Where found desirable, the heating jackets ofthe tanks being connected in parallel to the water cooling system, sothat ing solution without intermingling the liquids, whereb an emulsionis avoided, and producing a re a-tive movement between the liquids,whereby all parts of the contarninated oil are contacted with thewashing solution.

6. A process for washing contaminated oil which consists in heating aquantity of the oil, passing a layer of washing solution insubstantially sheet form from the top of the'oil to the bottom thereofwithout intermingling the liquids, thereby avoiding an emulsion, themovement of the washing solution past the oil being adapted to producecontacting currents in the oil, stopping the flow of washing solution,and allowing the suspended impurities to settle out of the oil.

In testimony whereof, I have hereunto set my signature. f CARL D.MILLER.

heat may be transferred from oil cooler 62 Y to several Washing tanks.

Having described my invention, what I- i claim as new and desire tosecure by Letters Patent of the United States is:

1. A method for washing oil, comprising passing a washing solutionthrough the oil in a substantially continuous sheet without suchagitation as will cause an emulsion.

9.. A method for washing lubricating oil, comprising heating a body ofoil, passing a soap solution downward therethrough in a substantiallycontinuous sheet, allowing the impurities to separate as sludge, andmechanically separating said sludge from the oil.

3. A process for washing a contaminated liquid which consists in passinga layer of a second liquid immiscible therewith and having the propertyof removing the contaminating substances therefrom in contact with alayer of the contaminated liquid, and changing the contacting surfaceswithout formlng an emulsion.

4. A process for washing a contaminated liquid which consists incontacting a layer of the contaminated liquid with a second liquidimmiscible therewith and having the property of removing thecontaminating substances therefrom without substantially interminglingsaid liquids, whereby an emulsion is avoided, and changing thecontacting layer ofcontaminated liquid, whereby all parts of saidcontaminated liquid are contacted with the washing liquid.

5. A process for washing contaminated oil which consists in contacting alayer of the contaminated oil with a layer of wash-

